Typical inexpensive pressure sensing systems are of the resistive type. By way of example, a resistive tank pressure sensor may use a floater that changes the output resistance if the tank level either rises or lowers. Although resistive tank sensors are inexpensive, they are not very accurate. Tank monitors that use fluid pressure are much more accurate, but much more expensive as well. While pressure sensors have been described in the art, such as the pressure sensor of U.S. Pat. Nos. 6,765,196 and 5,618,361 employing light beam interference between a transmitter and a receiver, a need exists for a pressure sensor that can provide a continuous monitoring of pressure value changes and at a low cost to the consumer.